This invention relates to orthopedic chairs and couches and, more particularly, to such seating adapted to move between reclined, upright and forwardly inclined positions.
In the past, orthopedic chairs designed to assist the user in moving between seated and standing positions typically included a tiltable seat whose rear portion moved upwardly relative to the back and armrests of the chair. Examples are disclosed in U.S. Pat. No. 4,907,303 to Baird and U.S. Pat. No. 4,778,217 to Lane. One of the perceived drawbacks to the chairs disclosed in these patents is their tendency to cause the user to stand or sit while his center of gravity is still shifting. Controlled tilting of the seat disclosed in Lane depends upon the user's ability to shift his weight between torso and legs in a balanced manner. If the user is unsteady and shifts his weight too far back or forward on the seat, pivotal movement of the seat would accelerate unless the user recovers his balance or the seat reaches a stopping point at a fully tilted or fully horizontal position. If either of these stops is reached suddenly, the user would be jarred into either a seated or standing position. The seat on Baird's orthopedic chair is pivotally connected to the frame at its front edge, so it is impossible for the user to control the movement of the seat simply by shifting his weight. Instead, Baird provides springs which serve as counterforces to the user's weight in moving the chair between horizontal and tilted positions. Even if the counterforce exerted by the springs is perfectly adjusted to accommodate a heavier or lighter user, an unintended shift in the user's weight during the raising or lowering movement could easily drive the seat to its upper or lower limit so rapidly as to destabilize and/or upset the user. In addition, the front edge of the Baird seat does not lower, so entry into, and exit from, the seat tends to require the user to be, or to place the user in, a relatively erect, straight-legged position.
Reclining orthopedic chairs have also been devised, but have lacked means to tilt forwardly in a manner which would aid the user in moving between seated and standing positions. The reclining chair disclosed in U.S. Pat. No. 4,732,423 to Condon is exemplary of this type. Although the seating assembly is pivotally mounted on a wheeled frame, a gas-hydraulic cylinder is so positioned below the seat as to prevent the seat from reaching a forwardly inclined position to any substantial degree. In addition, the pivot point on the Condon chair is disposed so far rearwardly that, even if the chair were capable of forward tilting, there would not be sufficient elevation of the rear portion of the seat to assist the user with ingress and egress. Furthermore, Condon's gas/hydraulic cylinder acts as a brake or a positioning device rather than as a means of assisting and/or damping pivotal movement.
Thus, the present inventors were faced with the problem of devising an orthopedic chair adapted to be reclined and to be tilted forwardly in such a manner as to assist the user in moving safely and easily between seated and standing positions.